High load time to time high iowait

[the_bobara]

Hello,
i have big problem with one of my servers.
I`m running CentOS 4.3 64bit with lastest stable cpanel.
Sometimes (a lot of times a day) the server load increase very fast. The server is working with load 0.x or 1.x and for seconds the load reach 80 - 100 - 140 sometimes even more than 250. When this happen i just stop apache, but this cant be the way.
I have read all the posts here, i spent a lot of nights googling but nothing helped. My current kernel is Linux 2.6.9-42.ELsmp #1 SMP the kernel before current was 2.6.9-34.ELsmp i changed a lot of kernels but nothing fixed my server. Now it happens once a day, but sometimes all day my server is crashing. Tell me what to do, i tried all the things that was posted here, has someone still have this problem? how the other manage to fix it?

here is the munin log of the system
P.S. sorry for my bad English

 

[avijit]

In the shell run "top -c" to get the idea on what is causing the loads to spike to that level and then you can troubleshoot it.

 

[the_bobara]

it happened again (see the attachment)
when i type top -c, i see a lot of httpd, but it is not pick time.

 

[spector]

I had exacly same issue with centos default install - high cpu usage by "iowait". You need to upgrade kernel manualy to newest (like 2.6.17.7) and problem will be gone instantly!

 

[the_bobara]

I`m now with 2.6.9-42.ELsmp kernel, i tried a lot of kernels. I have tried 2.6.9.34, 2.6.9.39 and a other...

 

[AndyReed]

I`m now with 2.6.9-42.ELsmp kernel, i tried a lot of kernels. I have tried 2.6.9.34, 2.6.9.39 and a other...

Although it is very hard to say without looking into your server, the problm might be something else other than the Kernel. It might be a hardware problem, or your server might come under serious attack.

 

[HostMerit]

We were using 2.6.14.6 and another kernel one ver higher with iowait / some load issues. The server just seemed sluggish.

2.6.17.8 seems to have solved all issues.

Dual Xeon 2.8 with SATA's.

 

[nickp666]

Although it is very hard to say without looking into your server, the problm might be something else other than the Kernel. It might be a hardware problem, or your server might come under serious attack.

I have the same issue which only occurred after the kernel upgrade, somewhere on the vbulletin forums is a large thread about it, seems to be an issue with that particular kernel

 

[trhosting.net]

I`m now with 2.6.9-42.ELsmp kernel, i tried a lot of kernels. I have tried 2.6.9.34, 2.6.9.39 and a other...

Both kernels you tried have this problem. You have to use 2.6.9-5.ELsmp or compile your own kernel from www.kernel.org.

 

[bin_asc]

It was said on vb forums, that a kernel 2.6.9-42.0.2 should be used, because the newer one is a kernel panic release, and it was causing issues in relation with the quota callouts.